/**
**********************************************************************
* @file     main.c
* @brief    对文件的简要说明
* @details  对文件的详细说明
* @author   jcai
* @date     2022-05-05 13:51:59
* @copyright Copyright &copy; 2022 wy1107412334@163.com All rights reserved
* @version  v0.0.1
*
* \n Email:  wy1107412334@163.com
* \n Blog:   None
* \n Github: https://github.com/wy1107412334
* \n Gitee:  https://gitee.com/git.git1107412334.com
*
**********************************************************************
* @note
* None.
**********************************************************************
* @attention
* None.
**********************************************************************
@verbatim
@endverbatim
**********************************************************************
* @par 历史记录
* 1. v0.0.1: jcai, 2022-05-05 13:51:59
*   - 首次编写
*
*<center>Copyright &copy; 2022 wy1107412334@163.com All rights reserved</center>
**********************************************************************
*/

/* 头文件导入区 --------------------------------------------------- */

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <SDL/SDL.h>
#include <SDL/SDL_video.h>
#include <SDL/SDL_ttf.h>
#include <SDL/SDL_image.h>
#include <SDL/SDL_events.h>
#include <SDL/SDL_timer.h>
#include <SDL/SDL_keysym.h>
#include <SDL/SDL_keyboard.h>


typedef struct
{
    int startTicks;
    int pausedTicks;
    int paused;
    int started;
} Timer_t;

// 窗口属性
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;

// 帧速率
const int FRAMES_PER_SECOND = 20;

// 将要使用的表面
SDL_Surface *back = NULL;
SDL_Surface *front = NULL;
SDL_Surface *screen = NULL;
SDL_Surface *message= NULL;

// 事件结构体
SDL_Event event;

// 使用的字体
TTF_Font *font = NULL;
// 字体颜色
SDL_Color textColor = {0x00, 0x77, 0x77};


SDL_Surface *load_image(const char *file)
{
    SDL_Surface *loadedImage = NULL;
    SDL_Surface *optimizedImage = NULL;

    // 通过 SDL_imag 模块加载图片
    loadedImage = IMG_Load(file);
    if (!loadedImage)   return NULL;

    optimizedImage = SDL_DisplayFormat(loadedImage);
    SDL_FreeSurface(loadedImage);
    if (optimizedImage)
    {
        // 映射关键色
        uint32_t keycolor = SDL_MapRGB(optimizedImage->format, 0, 0xff, 0xff);
        // 将所有颜色为 RGB(0x00, 0xff, 0xff) 的像素设为透明
        SDL_SetColorKey(optimizedImage, SDL_SRCCOLORKEY, keycolor);
    }

    return optimizedImage;
}

void apply_surface(int x, int y, SDL_Surface *src, SDL_Surface *dst)
{
    SDL_Rect offset;

    offset.x = x;
    offset.y = y;

    SDL_BlitSurface(src, NULL, dst, &offset);
}

int init()
{
    if (SDL_Init(SDL_INIT_EVERYTHING) == -1)
        return -1;

    screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP,
                              SDL_SWSURFACE);
    if (!screen)
    {
        SDL_Quit();
        return -2;
    }

    if (TTF_Init() == -1)
    {
        SDL_Quit();
        return -3;
    }

    SDL_WM_SetCaption("Alpha Test", NULL);

    return 0;
}

int load_files()
{
    // 加载背景图片
    back = load_image("fadein.png");
    if (!back)
    {
        return -1;
    }

    front = load_image("fadeout.png");
    if (!front)
    {
        SDL_FreeSurface(back);
        return -2;
    }

    font = TTF_OpenFont("lazy.ttf", 32);
    if (!font)
    {
        SDL_FreeSurface(back);
        SDL_FreeSurface(front);
        return -3;
    }

    return 0;
}

void clean_up()
{
    SDL_FreeSurface(back);
    SDL_FreeSurface(front);
    if (message)    SDL_FreeSurface(message);

    TTF_CloseFont(font);
    TTF_Quit();

    SDL_Quit();
}


void timer_init(Timer_t *tm)
{
    tm->startTicks = 0;
    tm->pausedTicks = 0;
    tm->paused = 0;
    tm->started = 0;
}
void timer_start(Timer_t *tm)
{
    tm->started = 1;
    tm->paused = 0;

    tm->startTicks = SDL_GetTicks();
}
void timer_stop(Timer_t *tm)
{
    tm->started = 0;
}
void timer_pause(Timer_t *tm)
{
    if (tm->started && !tm->paused)
    {
        tm->paused = 1;
        tm->pausedTicks = SDL_GetTicks() - tm->startTicks;
    }
}
void timer_unpause(Timer_t *tm)
{
    if (tm->paused)
    {
        tm->paused = 0;

        tm->startTicks = SDL_GetTicks() - tm->pausedTicks;
        tm->pausedTicks = 0;
    }
}
int timer_get_ticks(Timer_t *tm)
{
    if (tm->started)
    {
        if (tm->paused)
            return tm->pausedTicks;
        else
            return SDL_GetTicks() - tm->startTicks;
    }
    return 0;
}
int timer_is_started(Timer_t *tm)
{
    return tm->started;
}
int timer_is_paused(Timer_t *tm)
{
    return tm->paused;
}


/**
**********************************************************************
* @brief    简要说明
* @details  详细说明
* @param    none
* @param[in]     a: 该参数用于输入
* @param[in,out] b: 该参数用于输入和输出
* @param[out]    c: 该参数用于输出
* @retval  none
* @retval  0 函数成功
* @retval  1 函数失败
* @return  返回0成功；否则失败
* @note    none
*/
int main(int argc, char *argv[])
{
    Timer_t fps;
    int quit = 0;
    int32_t alpha = SDL_ALPHA_OPAQUE;

    if (init() != 0)
    {
        fprintf(stderr, "SDL初始化失败\n");
        return EXIT_FAILURE;
    }

    if (load_files() != 0)
    {
        fprintf(stderr, "SDL加载 background.png 失败\n");
        return EXIT_FAILURE;
    }

    timer_init(&fps);

    message = TTF_RenderText_Solid(font, "Press Up/Down Arrow keys.",
                                   textColor);

    while (!quit)
    {
        uint8_t *keystate;

        timer_start(&fps);

        // 处理SDL的事件
        while (SDL_PollEvent(&event))
        {
            // 如果用户点击了窗口右上角的关闭按钮
            if (event.type == SDL_QUIT)
            {
                quit = 1;
                printf("处理退出事件\n");
            }
        }

        keystate = SDL_GetKeyState(NULL);
        if (keystate[SDLK_UP])      // 上方向键被按下
        {
            if (alpha < SDL_ALPHA_OPAQUE)
                alpha += 5;
        }
        if (keystate[SDLK_DOWN])    // 下方向键被按下
        {
            if (alpha > SDL_ALPHA_TRANSPARENT)
                alpha -= 5;
        }
        SDL_SetAlpha(front, SDL_SRCALPHA, alpha);

        // 更新背景
        apply_surface(0, 0, back, screen);
        apply_surface(0, 0, front, screen);

        if (message)
            apply_surface((SCREEN_WIDTH - message->w) / 2,
                          0,
                          message,
                          screen);

        // 更新窗口
        if (SDL_Flip(screen) == -1)
        {
            fprintf(stderr, "SDL更新窗口失败\n");
            break;
        }

        // 控制帧速率
        if (timer_get_ticks(&fps) < (1000 / FRAMES_PER_SECOND))
            SDL_Delay((1000 / FRAMES_PER_SECOND) - timer_get_ticks(&fps));
    }

    clean_up();

    return 0;
}


/***  Copyright (C) 2022 wy1107412334@163.com All rights reserved ***/
/****************************** END OF FILE *************************/

